RESUMO
Objective To evaluate the pharmacokinetics of remifentanil in adult patients undergoing general anesthesia.Methods Ten ASA Ⅰ or Ⅱ adult patients of either sex undergoing elective surgery under general anesthesia were enrolled in this study.The patients were premedicated with atropine 0.5 mg.Anesthesia was induced with fentany1-2 ?g?kg~(-1),lidocaine 0.5-1.0 mg?kg~(-1),propofol 1.5-2.0 mg?kg~(-1) and vecuronium 0.1 mg?kg~(-1) and maintained with isoflurane -O_2 inhalation and intermittent i.v.boluses of vecuronium after tracheal intubation.The patients were mechanically ventilated.P_(ET)CO_2 was maintained at 30-40 mm Hg. Remifentanil 5 ?g?kg~(-1) was injected i.v.over lmin after induction of anesthesia.Arterial blood samples were taken before(baseline)and at 1,2,3,5,7,10,15,20,25,30,45,60 and 90 rain after drug administration for determination of blood remifentanil concentration using high performance liquid chromatography/mass spectrometry. The data were analyzed using 3P87 pharmacokinetic program.Results The pharmacokinetic profile of remifentanil was best described by a “two-compartment” model.The distribution half-life(t_(1/2?))(1.6?0.5)min,the elimination half-life(t_(1/2?))(22?10)min,total clearance(CL)(2.1?0.4)L/min and the volume of distribution (V_d)(66?29)L.Conclusion The volume of distribution calculated in this study is significantly different from that reported in previous studies,indicating that there may be some difference in the pharmacokineties of remifentanil between different populations.